A farting technique in which the flatulent person grabs one butt cheek and pulls the ass apart so that gas is expelled soundlessly, or almost soundlessly.
The manual release is sometimes accompanied by a subtly airy 'whooshing' or 'hissing' sound. Most dog farts make a similarly subtle sound, largely due to canines' utter lack of butt cheeks.
According to urban legend, this is also the same sound made by the fudge jar when a fart comes out. For example, one would expect the goatse man's flatulence to behave in this manner.
The most polite way to fart in public is the manual release.
...that is, unless someone sees you while you're gripping your butt cheek...then you may have to do some 'splaining.